Programmer Think

On December 25, when viewing the monitoring of a customer, it was found that the customer had executed page by page queries for more than 60s. The execution status is as follows: This is a very simple and typical page query SQL. khome_space.regdate column has an index, and the table has more than three million rows of data. The offset of the q ...

Building tables Create table tb and insert data: CREATE TABLE `tb_clazz` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT 'class id', `grade` varchar(64) DEFAULT NULL COMMENT 'Class name', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4; INSERT INTO `tb_clazz` (`id`, `grade`) VALUES ...

frame address: https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md Reference documents address: https://blog.csdn.net/she_lock/article/details/79975907 pom dependence <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</a ...

1, Spring Data JPA 1, introduction (1) Official website address:　　https://spring.io/projects/spring-data-jpaReference documents:　　https://docs.spring.io/spring-data/jpa/docs/2.2.3.RELEASE/reference/html/#preface (2) Basic introduction:Spring Data JPA is a set of JPA framework based on ORM framework and JPA specification encapsulation of spr ...

Mysql join table sql collation This paper sorts out some sql usage of mysql join table: Mysql join table sql collation TABLE statement Linked table query Linked list updating Linked list deletion view TABLE statement /*Table structure for table `departments` */ CREATE TABLE `departments` ( `department_id` int ...

Due to the needs of the company, it is necessary to change the transfer mode of IPOS friendly terminal group and IPOS friendly terminal group Because this operation is very troublesome and tedious, close-up this template, batch update and one click completion excel table format 2 tables in total At present, each store h ...

mysqld is the SQL daemons (that is, the MySQL server). To use the client program, it must run because the client accesses the database by connecting to the server. //Linux entry function int mysqld_main(int argc, char **argv){ ...... //Initialize operation //Cyclic connection mysqld_socket_acceptor->connecti ...

Master-slave replication: generally used for real-time backup. The next steps are as follows: master master database configuration synchronization, slave database configuration synchronization, master lock table / backup, slave data recovery, slave synchronization enabled, master unlocking, and completion. ##################### mysql5.7 bin-lo ...

score table: CREATE TABLE `score` ( `student_id` int(10) DEFAULT NULL, `class_id` int(10) DEFAULT NULL, `score` int(5) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci Field student ID student ID, class ID: class ID, score: Score Data preparation: insert into score values(1,1,100),(2,1,93 ...

Vernier [introduction] we can use the cursor to locate our mouse. If we want to find a specific row in the table, we can use the cursor to locate it. [general structure] declare cursor is sql statement begin open name; fetch a variable with the name into; exit when condition; close name end; [example 1] use the curso ...